Coated motion picture film



Feb. 6, 1934. L, STEELE 1,946,005

COATED MOTION PICTURE FILM Filed Feb. 28, -l929 CEL L ULOSE STER (NrrRocELLuLosE) PROTECTIVE LAYER AND ON ONE SIDE ONLY 0R HYGROSCOP/C ORGAN/CLow VOLATJLE MATERIAL v N BOTH SIDES (\SQLVENT' FOR CELLULOSE ESTER)(POLYGLYCOL) (DIETHYLENE sLvcoz.

ETHYL A LCOHOL BUTYL ACETATE MAY CONTAIN- BUTYL ALCOHOL TOLUOL LawrPatented Feb. 6, 1934 UNITED STATES COATED MOTION PICTURE EILM LawrenceL. Steele, Washington, I). 0., assignor to The Essem Washington, D. 0.,a

Laboratories,

Incorporated, corporation of Maryland Application February 28, 1929.Serial No. 343,568

Claims.

This invention relates to motion picture films and an object thereof isto provide such a film which is quite flexible and will maintain itsflexibility over extended periods of time during storage, particularlyin a dry atmosphere, and also will maintain its flexibility whensubjected to relatively high temperature in passing through the usualprojection machine.

It is also an object of the invention to provide a motion picture filmhaving a surface which shall be extremely highly resistant to marring orscratching incident to handling and particularly by the wear and tear onthe film incident to its passage through the projection machine.

It has heretofore been found that the usual motion picture filmcomprising a pyroxylin or other cellulose derivative base and a gelatinelayer will not maintain its flexibility but on the contrary will becomebrittle when stored over extended periods in a relative dry atmosphereand particularly when subjected to the temperatures evolved in theprojection machine. The generally accepted reason for this loss offlexibility of the film as a Whole is based on the deterioration of thepyroxylin material of which the foundation or backing layer is composed.However, I have found that this loss of flexibility is due mainly to theloss of moisture content of the gelatin layer. The present inventionproposes to coat the usual motion picture film on the gelatinside onlyor upon both sides with a cellulose ester material including in itscomposition an ingredient of a hygroscopic nature which will take upmoisture from the atmosphere and transfer it to the gelatin layer andthereby at all times maintain a sufllcient moisture content in thegelatin layer to thereby preserve a high degree of flexibility of themotion picture film. Preferably the hygroscopic ingredient employed isan organic material of low volatility and the best results are obtainedby the use of a coating wherein the hygroscopic material is also asolvent for cellulose esters. The use of such a material promotes agreatly improved bond between the gelatin layer and the coating.

45 In the accompany drawing I have, without restricting my inventionthereto, shown a film embodying my invention, the view being aconventional cross sectional showing on an enlarged scale.

In practicing the invention the motion picture film is provided upon thegelatin side only or upon both sides with a coating comprising as itsprincipal ingredients a cellulose ester such as nitro cellulose and apolyglycol preferably diethylene glycol. If desired, suitableproportions of the usual diluents may be employed as well as suitableproportions of other solvents of cellulose ester material. A coatinghaving its ingredients in the following proportions by weight has beenfound to be highly satisfactory, nitro cellulose 100 parts, diethyleneglycol 40 parts, butyl acetate 200- parts, butyl alcohol 150 parts,ethyl alcohol (denatured) 1250 parts, and toluol 1250 parts.

Diethylene glycol is a solvent for cellulose ester material and also hasmarked hydroscopic characteristics. It also acts as a plasticizer forthe cellulose ester coating material.

When the coated film is subjected to the drying action of the atmosphereor to the heat of the projection machine, sufficient moisture is takenfrom the atmosphere by the hygroscopic action of the polyglycol, andtransferred to the gelatin to thereby maintain the necessary moisturetherein and thereby prevent the film from becoming brittle. By reason ofthus maintaining the desired moisture content of the gelatin layer itwill be found that the flexibility of the film is preserved and bucklingand shrinking thereof is prevented. The coating of the invention is alsocharacterized by the quality of resistance to scratching by virtue ofits hardness, comprising for the most part in the preferred form nitrocellulose and diethylene glycol.

What I claim is:

1. A developed motion picture film having a protective coatingcomprising a cellulose ester and a hygroscopic organic material of lowvolatility.

2. A developed motion picture film having a protective coating on thegelatin side only comprising a cellulose ester and a hygroscopic organicmaterial of low volatility.

3. A developed motion picture film having a protective coatingcomprising nitro cellulose and a hydroscopic organic material of lowvolatility.

4. A developed motion picture film having a protective coating on thegelatin side only comprising nitro cellulose and a hygroscopic organicmaterial of low volatility.

5. A developed motion picture film having a protective coatingcomprising a cellulose ester and a hygroscopic solvent therefor of lowvolatility.

6. A motion picture film having a coating comprising a cellulose esterand a polyglycol.

7. A motion picture film having a coating comprising a cellulose esterand diethylene glycol.

8. A developed motion picture film having a protective coatingcomprising nitro cellulose and a hygroscopic solvent therefor of lowvolatility.

9. A motion picture film having a coating comprising nitro cellulose anda polyglycol.

10. A motion picture film having a coating comprising nitro celluloseand diethylene glycol.

LAWRENCE L. STEELE.

